The present invention relates to optical communication techniques. More particularly, the present invention provides a surface gratings device for optical input/output, a wafer level integrated circuit for a photonics optical system, and method of using thereof.
Over the last few decades, the use of communication networks exploded. In the early days Internet, popular applications were limited to emails, bulletin board, and mostly informational and text-based web page surfing, and the amount of data transferred was usually relatively small. Today, Internet and mobile applications demand a huge amount of bandwidth for transferring photo, video, music, and other multimedia files. For example, a social network like Facebook processes more than 500 TB of data daily. With such high demands on data and data transfer, existing data communication systems need to be improved to address these needs.
Progress in computer technology (and the continuation of Moore's Law) is becoming increasingly dependent on faster data transfer between and within microchips. Optical interconnects may provide a way forward, and silicon photonics may prove particularly useful, once integrated on the standard silicon chips. Surface gratings are important form of optical input/output (IO) since they allow us to do wafer level testing which is essential for product line of making photonics systems on chips. For example, surface grating can be put in form of the array of input/outputs using the fiber array as an optical probe, multiple outputs can be measured simultaneously with only one alignment. Other forms of IO such as edge coupling, requires dicing before testing. Also, it is more time consuming as each die and component should be tested separately with a single fiber. Separate alignment is also necessary for each input and output. Additionally, surface grating can be utilized for a single polarization or as a polarization diverse component. The later can be used for measurement of the polarization sensitive components where both sources of TE and TM are launched to the wafer.
Most conventional polarization splitting gratings are able to provide polarization light in either TE or TM polarization mode to the wafer but with poor coupling efficiency. The conventional grating coupler for polarization diverse that provides both TE and TM polarization light are large in size as they cannot use focusing configuration. Therefore, an improved surface grating device with either polarization splitting or diverse function is desired to be integrated in a photonics system.